The ITU-R is an advisory body and is not binding in any legal sense. Each country has special circumstances. We have 2 million CB sets looking for a amplifier to mate with.

It does not matter what the mode the amplifier is operated in, it will still have to meet harmonic specs of TIA-603C USA (Commercial) if it has gain above 21.45 MHz. That is out to the tenth harmonic.

The FCC is concerned about out of band emissions. In band you can splatter all you want. The adjustment of the amplifier input is not a function of the device but of the person using the device. Most hams would fry the grids if there was not a grid trip on modern amplifiers. Modern amplifiers are hard enough to build and maintain a profit given most hams have no idea how to connect a linear and tune it properly. This is why new amps have so much fault monitoring.

Amplifiers are not considered emitters and do not come under the same technicals as transmitters.

The only part the FCC got wrong on amplifier requirements is the overly stringent case emissions requirements of -70 dBc (1 KW) being the same as the harmonics. As soon as you connect a amplifier to a local antenna your case emissions will only be down 10-20 dBc. This is what happens when you hand over a technical specification to a lawyer.

Also the FCC requires no gain in the 26-28 MHz region for any amplifier. I believe Europe does not have that requirement.

That case emission requirement must be a bear to meet, box within a box anyone?

EU does not have any requirement not to provide gain at 11m, and most EU solid state amps will quite happily do so, particularly if they cover 10m, to do otherwise requires extra circuity (or code) for no benefit in the European market. I suspect that many valve amps over here have enough tuning range to get there on a nominally 10m setting as well.

The high power SSB on 11m is a US phenomenon as far as I can tell, it probably helps that EU CBs are FM only, so even where people are using amplifiers the opportunities for splatter are less as there is no envelope modulation.

Although ITU-R Recommendations are just that, by a very tortuous route through the Radio Regulations, SM329 applies. The Radio Regulations are international law - the Head of Delegation of the US delegation to a WRC is usually of Ambassador status. Even so, they get sent ecponomy class across the pond!

Regardless crudding the band up with a cheap CB amplifier is not the right thing to be doing on the hams bands. Increasing the noise floor of the ham bands just to accommodate cheap CB amplifiers and new operators budgets is not smart. Whats going to be next, are we going to allow Class C amplifiers to be used on SSB just because new operators cant afford a decent clean legal amplifier. We just opening a can of worms by even discussing using these crap amplifiers on the ham bands. Why are we giving in promoting the worst possible standards for the ham bands by using such equipment as the RM Italy amplifiers, is Dave Made and FAt Boy amplifiers the next kid off the block for new hams?

The ITU-R is an advisory body and is not binding in any legal sense. Each country has special circumstances. We have 2 million CB sets looking for a amplifier to mate with.

It does not matter what the mode the amplifier is operated in, it will still have to meet harmonic specs of TIA-603C USA (Commercial) if it has gain above 21.45 MHz. That is out to the tenth harmonic.

The FCC is concerned about out of band emissions. In band you can splatter all you want. The adjustment of the amplifier input is not a function of the device but of the person using the device. Most hams would fry the grids if there was not a grid trip on modern amplifiers. Modern amplifiers are hard enough to build and maintain a profit given most hams have no idea how to connect a linear and tune it properly. This is why new amps have so much fault monitoring.

Amplifiers are not considered emitters and do not come under the same technicals as transmitters.

The only part the FCC got wrong on amplifier requirements is the overly stringent case emissions requirements of -70 dBc (1 KW) being the same as the harmonics. As soon as you connect a amplifier to a local antenna your case emissions will only be down 10-20 dBc. This is what happens when you hand over a technical specification to a lawyer.

Also the FCC requires no gain in the 26-28 MHz region for any amplifier. I believe Europe does not have that requirement.

On a related note, anyone can now download the ITU standards such as SM329 without registering or paying now. Maybe if more hams actually read SM329 they would not be so reluctant about mandatory IMD standards.

We want to fight things like BPL and we dont have the common sense to see that the widespread use of poor IMD CB amplifiers could make the same mess of the bands, some hams just dont get it!

Although ITU-R Recommendations are just that, by a very tortuous route through the Radio Regulations, SM329 applies. The Radio Regulations are international law - the Head of Delegation of the US delegation to a WRC is usually of Ambassador status. Even so, they get sent ecponomy class across the pond!

< < CB amplifiers could make the same mess of the bands, some hams just dont get it! > >

ZENKI…………………………………… I just don’t get it ?? I have been a Ham way to long and can’t tell you the last time I chase down someone using a dirty CB Amp on HF.

As Mike posted the top ten reasons above………. I have to listen to every time I get on the air ! Can you start Bashing those guys a little more and worry less about a guyusing a RM Italy to power up ones QRP/ CW Rig. I didn’t see a CB Amp on Mike’s list, so I don’t think he is going Atomic over this being a major problem on the air. Suresome might be running dirty, but don’t stand on my foot ! Let see how many other Hams have had continuous trouble with CB Amps on HF ?

There is a problem with ITU-R Rec SM.329 applied to amateur service equipment at UHF and above. If you ran CW for EME at 10 GHz and 500 watts, the way SM.329 is written you would have an impossible job to meet it because of phase noise - or of measuring it if you did.

The European interpetation of SM.329 is ERC-REC 74-01, and it takes phase noise into account in setting the levels.

Yep amplifiers are largely an irrelevance as long as we are leaving so much of the transmit chain under manual control.

It is not actually that hard to design an audio frequency limiter working in the analytic domain that will successfully limit the peak envelope of the resulting SSB signal (Note that a limiter working in real as opposed to analytic space will NOT do the right thing), without requiring any ALC feedback loop at all, particularly in a world increasing using DSP in the transmit path. The SSB envelope is bounded by sqrt (I^2 + Q^2), not by |I|.

Once you have a band limited signal that is limited so as not to cause overload on envelope peaks when converted to SSB, then adding a front end audio AGC/Compressor/Gate arrangement is not really rocket science, and you can if you must, expose those controls to the user without any risk that they will be able to cause out of channel problems.

It is only ham gear that provides the controls to allow AKTTR to cause interference, everyone else, even if they provide the knobs, includes circuitry to keep the user from screwing up adjacent channels.

An additional refinement would be to measure |I|, |V| at the output of the PA then |Z| could be trivially calculated which could be used by the baseband DSP to throttle the drive power so that operation into 1.5:1 or worse would still be clean.

None of this is rocket science, and some of it is merely trivial software changes to any rig using DSP based phasing or weaver method SSB generation, yet removing the ability to have screwing up with the audio controls cause problems other then your own intelligibility would be a huge win.

Amplifier IMD is actually a second tier problem compared to exciter IMD especially exciters that fall to bits when operated by the technically ignorant.

I've been corresponding with the FCC about external amplifiers and received this message regarding external amplifiers that are market for sale to amateurs in the U.S.:

Quote

Hello,

Section 2.1049 applies to Certification. Part 97 devices do not require Certification except for amplifiers. What we are looking for in amplifier Certification are intermodulation products and notching of the 26-28 MHz band. Technical and Certification requirements are in Sections 97.315 and 97.317.

Regards,

Andy LeimerFCC/OET/EACB

So, I had to dig through 47 CFR 2.1049, which led me to 2.1046(b)(3), which states:

Quote

(3) As an alternative to paragraphs(b) (1) and (2) of this section othertones besides those specified may beused as modulating frequencies, upon asufficient showing of need. However,any tones so chosen must not be harmonicallyrelated, the third and fifthorder intermodulation products whichoccur must fall within the ¥25 dB stepof the emission bandwidth limitationcurve, the seventh and ninth orderintermodulation product must fallwithin the 35 dB step of the referencedcurve and the eleventh and all higherorder products must fall beyond the¥35 dB step of the referenced curve.

So, it seems that IMD product measurement and verification are part of the external amplifier certification process. I think.

If so, the amplifier that's subject of this thread wouldn't meet the certification requirements when operated at its stated power output (and earlier in Part 2, Subpart J it does specify that amplifiers must be tested at 1500W output, or their maximum rated output power, whichever is less).

The rated output is for test certification only. In that the amplifier meets all related FCC requirements at rated output or below. The amplifier can be capable of more output than the rated output. I have tested amplifier for certification that were capable of almost 3 dB more output.

The rated output is for test certification only. In that the amplifier meets all related FCC requirements at rated output or below. The amplifier can be capable of more output than the rated output. I have tested amplifier for certification that were capable of almost 3 dB more output.

Mike, that makes sense. In fact, it makes a whole lot of sense since almost any kind of amplifier probably is more linear and has better IMD performance when throttled back from "max."

Unfortunately "marketing" often wins over "engineering," and crazy claims are made. I just reviewed the old Henry 3K-A manual for a local guy who just bought a used one, and see even Henry went wild the the specs on that amp. "2000W PEP output" are listed all over the place, and that output is even specified for RTTY.

Its power supply can probably do that just fine, but you're pushing a pair of 3-500Zs up there.

When doing the external amplifier certification routine for a Part 97 amp, is IMD included in the measurement and data?

I've overseen a lot of "certification testing" for various products, but never a ham amplifier, so this is unclear to me.

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